This section is from the book "Nature's Garden", by Neltje Blanchan. Also available from Amazon: Nature's Garden; An Aid To Knowledge Of Our Wild Flowers And Their Insect Visitors.
Flowers - Blue to pinkish and whitish, 1 to 1 1/2 in. long, hung on slender stems, and scattered along spreading branches; 5 petal-like sepals, the rear one prolonged into long, slender, curving spur; 2 petals, united. Stem: 1 to 2 1/2 ft. high. Leaves: Divided into very finely cut linear segments.
Fruit: Erect, smooth pod tipped with a short beak; open on one side.
Preferred Habitat - Roadsides and fields.
Flowering Season - June - August.
Distribution - Naturalized from Europe; from New Jersey southward, occasionally escaped from gardens farther north.
Keats should certainly have extolled the larkspurs in his sonnet on blue. No more beautiful group of plants contributes to the charm of gardens, woods, and roadsides, where some have escaped cultivation and become naturalized, than the delphinium, that take their name from a fancied resemblance to a dolphin (dolphin), given them by Linnaeus in one of his wild flights of imagination. Having lost the power to fertilize themselves, according to Muller, they are pollenized by both bees and butterflies, insects whose tongues have kept pace with the development of certain flowers, such as the larkspur, columbine, and violet, that they may reach into the deep recesses of the spurs where the nectar is hidden from all but benefactors.
The Tall Wild Larkspur (D. urceolatum, or D. exaltatum of Gray) waves long, crowded, downy wands of intense purplish blue in the rich woods of Western Pennsylvania, southward to the Carolinas and Alabama, and westward to Nebraska. Its spur is nearly straight, not to increase the difficulty a bee must have in pressing his lips through the upper and lower petals to reach the nectar at the end of it. First, the stamens successively raise themselves in the passage back of the petals to dust his head; then, when each has shed its pollen and bent down again, the pistil takes its turn in occupying the place, so that a pollen-laden bee, coming to visit the blossom from an earlier flower, can scarcely help fertilizing it. It is said there are but two insects in Europe with lips long enough to reach the bottom of the long horn of plenty hung by the Bee Larkspur (D. elatum), that we know only in gardens here. Its yellowish bearded lower petals readily deceive one into thinking a bee has just alighted there.
From April to June the Dwarf Larkspur or Stagger-weed (D. tricome), which, however, may sometimes grow three feet high, lifts a loose raceme of blue, rarely white, flowers an inch or more long, at the end of a stout stem rising from a tuberous root. Its slightly ascending spur, its three widely spreading seed vessels, and the deeply cut leaf of from five to seven divisions are distinguishing characteristics. From Western Pennsylvania and Georgia to Arkansas and Minnesota it is found in rather stiff soil. Butterflies, which prefer erect flowers, have some difficulty to cling while they drain the almost upright spurs, especially the Papilios, which usually suck with their wings in motion. But the bees, to which the delphinium are best adapted, although butterflies visit them quite as frequently, find a convenient landing place prepared for them, and fertilize the flower while they sip with ease.
More slender, downy, and dwarf of stem than the preceding is the Carolina Larkspur (D. Carolinianum), whose blue flowers, varying to white, and its very finely cleft leaves, may be found in the South, on prairies in the North and West, and in the Rocky Mountain region.